SPC AC 180550

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1250 AM CDT Sat May 18 2024

   Valid 191200Z - 201200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
   OF WESTERN AND CENTRAL KANSAS...

   ...SUMMARY...
   Severe thunderstorms are most likely across parts of Kansas Sunday
   afternoon and evening. Significant damaging gusts, large to very
   large hail, and a few tornadoes all appear possible.

   ...NE/KS/OK...

   A weak upper shortwave impulse over NE Sunday morning will quickly
   lift northeast. Some convection may be ongoing across NE/KS during
   the morning, but is forecast to quickly weaken/shift east. This
   early activity may suppress severe potential across northeast NE
   during the afternoon as airmass recovery is uncertain. By afternoon,
   another upper shortwave trough is forecast to eject from the
   southern/central Rockies into KS, and then the Lower MO Valley by
   Monday morning. This secondary shortwave trough will be the focus
   for the primary severe risk during the afternoon/evening.

   A surface dryline is forecast to extend southward from near the
   NE/KS/CO border into western KS and then near the OK/TX border. To
   the east of the dryline, dewpoints into the low/mid 60s are expected
   across OK into central/eastern KS (somewhat lower across northern KS
   and southern NE). Very steep midlevel lapse rates (greater than 8
   C/km) will be in place. Capping will suppress convection until
   mid/late afternoon, when large-scale ascent increases amid strong
   heating and continued warm/moist advection. High-based storms along
   the dryline will initially pose a risk of large hail and damaging
   gusts. Forecast guidance (including HREF and CAMs) show a strong
   signal for upscale growth into an intense bow is possible across KS.
   Upscale growth is possible via consolidating outflow and an
   increasing low-level jet during the late afternoon/early evening.
   Significant gusts will be possible if this scenario evolves as
   expected. Large to very hail and a few tornadoes also will be
   possible. Hail greater than 2 inches in diameter will be possible
   early in convective evolution, but eastward extent of this risk is
   uncertain and dependent on storm mode. 

   Severe potential southward along the dryline into western OK is more
   uncertain and conditional. If a storm can develop and be maintained,
   all severe hazards would be possible, particularly very large hail
   and damaging gusts.

   ...SD vicinity...

   Southerly low-level flow will transport mid/upper 50s F dewpoints
   northward into northern NE/SD and southern ND. A cold front is
   forecast to develop eastward during the late Sunday afternoon into
   Sunday night. Steep midlevel lapse rates will be in place, but an
   EML will likely limit a greater severe risk. Nevertheless, MUCAPE to
   around 1500 J/kg will support elevated convection ahead of the cold
   front. Isolated hail will be the main risk. However, if an organized
   line of storms can develop, some gusty winds also are possible. 

   ...Lower MO Valley toward the Mid-MS Valley...

   Convection from NE/KS may dissipate over the area during the
   morning. However, a warm front is expected to slowly lift northward
   through the day, allowing from some airmass recovery and
   destabilization. Convection may redevelop near this boundary during
   the afternoon. This activity may produce marginally severe hail and
   gusty winds.

   ...FL...

   An upper trough from the Mid-Atlantic to the northern Gulf will
   shift east over the Atlantic on Sunday. A belt of enhanced
   west/southwesterly flow (30-40 kt at 700 mb) will overspread the FL
   peninsula ahead of the trough. Mid to upper 60s F surface dewpoints
   and strong heating will contribute to MLCAPE values around 1500-2500
   J/kg. Steep low-level lapse rates will support isolated strong gusts
   in water-loaded downdrafts. Elongated/straight forecast hodographs
   and modest midlevel lapse rates (6.5-7 C/km) suggest isolated large
   hail also is possible. Effective shear around 30 kt suggests
   organized updrafts may be somewhat transient. If confidence
   increases regarding coverage of organized severe convection, higher
   probabilities may be needed in subsequent outlooks.

   ..Leitman.. 05/18/2024

   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z